Uniformly dispersing fibers

ABSTRACT

A sized staple fiber product that disperses quickly, thoroughly and uniformly in water is particularly useful in the manufacture of gypsum board by the slurry process. An aqueous chemical size composiiton on the surface of the fibers contains a high level of surfactant and can contain a polymer film former and a biocide. Preferably, the fiber is chopped glass fiber. Novel sizing composition and methods of making and using the fiber are also disclosed.

[0001] The invention involves a glass fiber having a chemical sizingapplied on the surface to allow the fiber to disperse quickly anduniformly in plain water, the sizing composition and the methods ofmaking and using the sized fiber.

BACKGROUND

[0002] Inorganic staple fiber including glass fiber, ceramic fiber andmineral fiber like mineral, glass or slag wool have been usedextensively for reinforcing numerous materials and for enhancing thefire resistance of products. For example, glass fiber has been used toreinforce and enhance the fire resistance and rating of gypsum board.

[0003] At least two processes are typically used for adding glass fiberin the manufacture of gypsum board. The first process feeds dried glassfiber having a low moisture content and a chemical sizing on the fiberinto wetted calcined gypsum, usually while the wetted material is beingmixed and transported in an auger mixer. The fiber is dispersed in themix by the mixing action. The second process involves adding the fiberdirectly into the water to make a slurry for a gypsum board before otheringredients are added. The water is typically a low quality, such as tapwater, well water, lake or river water, i.e. plant water. The secondprocess using low quality water is preferred by some manufacturers. Forthe second process, it is necessary that the fiber disperse quickly anduniformly. If it doesn't, each cubic inch of the board won't have enoughfibers to pass the fire test and excess fiber will have to be used toinsure enough fibers are in each portion of the board.

[0004] Unfortunately, the low moisture fiber made for feeding into thewetted gypsum mixture does not disperse uniformly and quicklynecessitating that excess dry fiber be used or that a dispersant beadded to the water prior to adding the fiber. Some dispersants found towork marginally in dispersing the dry fiber are flammable, presenting anundesirable risk to the manufacturing plants using the fiber.

[0005] Other glass fiber products are available in both dried and havinga higher moisture content, both with a chemical sizing thereon dependingon the intended application. Almost all glass fibers have a chemicalsizing on their surface to protect the surface from abrasion andscratches during manufacture and use which will substantially reduce thestrength of the fiber. The chemical sizing also can function to aiddispersion and to provide a better bond between the glass fiber and amatrix that the fiber will reinforce, such as a plastic material, aresin binder, etc.

[0006] Dry glass fiber products intended for use in plastics productswill not disperse sufficiently in water and therefore are not suitable.Various wet chop fiber products, i.e. undried, chopped continuous glassfiber for use in making nonwoven mats in wet process machines or papermachines also did not disperse sufficiently. The sizing on these latterfiber products is designed to cause the fiber to disperse well in a“whitewater” and to bond well to a urea formaldehyde or acrylic resinbinder and apparently for that reason do not separate well in plainwater, i.e. water without one or more dispersants added. Whitewater usedin wet process machines for making mats, unlike plain water in thegypsum board slurry process, contain various viscosity modifiers,defoaming agents, dispersants and other chemical additives that permitthe fibers to disperse as desired.

[0007] Therefore, there is a need for a fiber product having a chemicalsizing thereon that will permit the fiber to disperse quickly,adequately and uniformly in plant water.

SUMMARY OF THE INVENTION

[0008] The present invention includes a staple inorganic fiber having achemical sizing, having a very high surfactant level on its surface. Thefibers resulting are advantageous in any process where it is desired todisperse inorganic fiber in plant water. The invention also includes asize composition for inorganic fibers and a method of making a choppedinorganic fiber product for use in dispersing in plant water in aprocess for making a fiber reinforced product such as gypsum board. Theterm “staple” includes fibers of various lengths under a few incheslong. The fibers can all be of generally the same length or can be amixture of lengths. For the present invention, lengths of less than 1.5inches, such as one-half, one, three-fourths, one-quarter, etc. inchlong are preferred. A length of one-half inch is particularly suitablefor making gypsum board.

[0009] The novel size composition on the glass fiber comprises a plantwater, deionized water, or distilled water, a high level of surfactantand preferably a film former polymer like polyvinyl alcohol, and cancontain a biocide to retard microbial action. The surfactant ispreferably a poly (Oxy-1,2-ethanediyl), alpha(2-(bis(2-Aminoethyl)Methyl-ammonio) Ethyl)-omega-Hydroxy-,N,N′-Di(C 14-18 and C 16-18unsaturated) Acyl Derivs., Me Sulfate (Salts). The sizing compositioncontains about 0.1-1.2 wt. percent surfactant, preferably about 0.3-0.9wt. percent and most preferably about 0.6+/−0.1 wt. percent. Other knownsurfactants compatible with water and known to act similarly to thefamily of surfactants mentioned just above can be used individually orin combination to replace all or a portion of the family of surfactantsdescribed just above.

[0010] The film former polymer is preferably present in amounts up to1.5 wt. percent, preferably about 0.2-0.8 wt. percent and mostpreferably about 0.5 +/−0.1 wt. percent. All weight percentages of thesizing composition are based on the total weight of the sizing includingwater. When a biocide is used, it is present in effective amounts forthis function and that can vary depending on the particular biocidechosen.

[0011] The fiber product can be dry or can contain up to about 25percent moisture. Preferably the fibers are glass fibers chopped inlengths less than 1.5 inches, such as one-half, one, three-fourths,one-quarter, etc. inch long. The fibers can be of any suitable diameter,preferably between 5-23 micron. The fibers have a loss on ignition, dueto the chemical sizing on their surfaces, of about 0.08-0.24 percent andpreferably about 0.1-0.21 wt. percent and most preferably about0.13-0.19 percent with a target of about 0.16 wt percent. The surfactantis at least about 30 wt. percent of the LOI and preferably at least 40wt. percent up to as much as about 60 wt. percent with a film formermaking up the remainder with the exception of a minor, effective amountof a biocide. The fibers are made according to known processes, butusing the inventive size composition to coat the fibers in place ofconventional sizing compositions. The invention also includes the methodof using the inventive fibers in processes for making fiber reinforcedproducts where the fibers are dispersed in plant water as an early stepin the process, such as a process for making gypsum board.

DETAILED DESCRIPTION OF THE INVENTION

[0012] Chopped or staple inorganic fiber for use in reinforcements canbe made using a number of different processes as is well known. Thepreferred process for making the preferred embodiment of the presentinvention which is a chopped sized glass fiber product is a well knownprocess such as shown in U.S. Pat. Nos. 4,692,178, 4,194,896, and3,869,268, the disclosures of which are incorporated herein byreference. Other processes for making mineral wool, staple glass orceramic fibers having a chemical sizing on the longitudinal surfaces ofthe fibers would also be suitable. In the processes for making thepreferred embodiments of the invention, which comprise continuouslychopped fiber glass strands, glass fibers are pulled from fiberizers ina known way. A water mist is sprayed on the hot fibers to cool thefibers and then the fibers are pulled over a chemical sizing applicatorwhere a chemical sizing, preferably an aqueous chemical sizing, iscoated onto the fibers by bringing the fibers into contact with a curvedsurface having a layer of sizing thereon. The coated fibers are thenpulled as a strand, usually along with several other strands of sizedglass fibers, into a continuous chopper where the strands are choppedinto desired lengths and discharged onto a conveyor, a dryer or into apackage.

[0013] When it is desired to dry the fibers partially or completely, avibrating fluid bed dryer like that shown in U.S. Pat. No. 4,840,755, orany suitable dryer, can be used. When it is desired to package thefibers without further drying, the discharged chopped fibers aredischarged directly or indirectly into a plastic bag and sealed forshipment.

[0014] The fibers are preferably glass fibers and preferably E(electrical) and T (chemical resistant) glass fibers although othertypes of glass fibers including C, insulation glass, S, and R glassfibers are usable in the present invention. Any desired length issuitable; however, fiber to make gypsum board is preferably one-halfinch long fibers. The chopped strands typically contain at least 2000fibers each, but can contain substantially less and up to 4000 or morefibers. The diameter of the fibers can be any desired diameter withinreason and usually the average fiber diameter is between 5 and 23microns. Most typical products have fiber diameters of 16+/−1 micron or13+/1 micron, but the fiber diameter is not critical to the invention.

[0015] In practice, the sizing of the present invention is applied tothe fibers according to one of the processes described above, or theaqueous sizing is sprayed onto the fibers while the fibers are suspendedin the air in the known processes of applying binder to staple fibersfor making fiber insulation products. The sizing is applied to thefibers in such concentrations to produce a fiber product having a losson ignition (LOI) due to the chemical sizing in a range of 0.08-0.24weight percent, based on the dry weight of the fiber product, preferablywithin a range of 0.11-0.21 wt. percent and most preferably 0.16+/−0.03wt. percent. The chemically sized fiber can be dried completely, butpreferably the sized fiber is packaged wet with a moisture content inthe range of about 5-25 wt. percent, preferably in the range of about10-20 wt. percent and most preferably in the range of 15+/−2 wt.percent.

[0016] The sizing composition of the present invention contains plant,deionized or distilled water, preferably plant water, a very level ofsurfactant, compared to conventional sizings for fibers, in an. amountof about 0.1 to about 1.2 wt. percent, preferably about 0.3-0.9 wtpercent, and most preferably about 0.5-0.7 wt. percent, based on theweight of a sizing batch. The surfactant is preferably a poly(Oxy-1,2-ethanediyl), alpha(2-(bis(2-Aminoethyl) Methyl-ammonio)Ethyl)-omega-Hydroxy-, N, N′-Di(C 14-18 and C 16-18 unsaturated) AdylDerivs., Me Sulfate (Salts) and most preferably is Varisoft™ 222LTavailable from the Witco Corporation of Dublin, Ohio. Verisoft™ SDC,available from the same company, is also suitable. The Varisoft™ 222 LTcontains 80-95 percent of Methyl bis(Alkylamidoethyl) 2-HydroxyethylAmmonium Methyl Sulfate, Ethoxylated surfactant and 5-15 percentisoproponol, has an approximate specific gravity of 0.98 at 73 degreesF., a vapor pressure of 33 mm/Hg at 68 degrees F. and an NIT boilingpoint of 180 degrees F. at 760 mm Hg. Other known surfactants can beused, alone or in combination, to replace all or part of the specificsurfactants described above. Such surfactants include glycols, fattyacid tallow amines like CAT-X™, Aromox™ DM-16 and DMHT and others, butthe surfactant Varisoft™ 222 LT disperses optimally.

[0017] The sizing composition of the present invention can also containa polymer film former, preferably a polymer film former like polyvinylalcohol, a hydroxyethyl cellulose, a polyacrylamide or other known filmformer for fiber sizing in an amount in the range of 0 to about 1.5 wt.percent, preferably in the range of about 0.25-about 0.75 wt percent andmost preferably about 0.4-0.06 wt. percent. The primary purpose of thefilm former is to protect the surface of the fiber, if necessary. Also,if the surfactant is used in a concentration near the high side of theacceptable range, a film former might not be needed in the sizing.However, due to the higher cost of the surfactant, and higher fiberprocessing cost at the higher levels, it is preferred to use a filmformer in the sizing composition in the above amounts.

[0018] A vinyl polymer film former such as for example polyvinyl alcoholis preferred and one preferred polyvinyl alcohol film former isavailable from Air Products and Chemicals, Inc. of Allentown, Pa. underthe tradenames of Vinol™ or AIRVOL™ and most preferably is AIRVOL™ 205.Other known polyvinyl alcohol film formers for fiber sizing compositionsmay also be suitable.

[0019] When it is desired to protect the sizing in storage or on thefiber from bacterial or microbial activity, a biocide is included in thesizing in an effective amount for this function and the amount will varydepending on the particular biocide chosen. Preferably a biocide such asfor example Chemtrea™ CL 206 or CL 2150 is used, preferably in an amountof about 0.084 wt. percent, but other known biocides may also be used ineffective amounts. Biocide may not be necessary if the sized fiber isdried or if the wet fiber is used within a short period of time or if anunpleasant aroma is not deemed a problem. If excessive bacterial actionis allowed, the sizing may not perform satisfactorily. Preferably, abiocide is included to prevent bacterial action.

[0020] The amount of sizing on a fiber is determined by subjecting thefiber to the well known loss on ignition test, or “LOI” test. Toaccomplish an LOI test, a sample of sized fiber is weighed carefully andthoroughly dried and weighed again to determine the moisture content ofthe fiber, based on the dry weight of the fiber. The fiber is put into afurnace at a temperature exceeding 1000 degrees F. and having an airatmosphere to drive off all volatiles from the sizing and to burn offall organic materials in the sizing.

[0021] Thereafter, the fibers are weighed again to determine the weightof the bare fibers. The difference between the dry weight and the barefiber weight is then used to calculate the amount of dry sizing on thefibers, based on the weight of the bare fibers. Based on LOI, theresulting fiber product of the present invention has from about 0.08 toabout 0.24 weight percent of dry sizing on the fiber, preferably about0.12 to about 0.2 weight percent and most preferably about 0.16+/−0.03wt. percent. Of the dry sizing on the dry fiber, the cationic surfactantingredient will preferably constitute at least about 30 wt. percent,preferably at least, 40 or 45 wt. percent, up to about 60 wt. percent,and most preferably about 42-48 wt. percent. A film former willpreferably be present and constitute at least about 20 wt. percent ofthe LOI, preferably about 35-50 wt. percent or more, and most preferablyabout 39-46 wt. percent. The fiber product of the present invention canbe dry, but preferably is wet having a moisture content of about 5 toabout 25 weight percent, preferably about 15+/−2 wt. percent.

[0022] When the fiber product of the present invention is added, such asby dumping or feeding slowly, to plain plant water, containing nodispersants, the fiber quickly disperses thoroughly and uniformly asdesired and in a substantially different and superior degree comparedwith previous staple glass fiber products. This is very useful in anyprocess where it is desirable to disperse fiber in plant water. Thepresent fiber product is particularly useful in the process of makinggypsum board in a processes like that disclosed in U.S. Pat. No.4,241,136, the disclosure of which is incorporated herein by reference,and other similar processes of making gypsum board where early in theprocess the fiber is added to plant water.

EXAMPLE

[0023] An aqueous sizing batch was made, containing plant water, in thiscase city water, 0.6 wt. percent of Varisoft™ 222 LT surfactant, 0.5 wt.percent AIRVOL™ 205 and 0.084 wt. percent Chemtreat™ CL 206. Allpercentages are based on the weight of the finished aqueous sizingcomposition. This sizing was applied to water wet E glass fiberscontinuously in a known manner and the fiber was chopped continuouslyinto one-half inch lengths. The fiber making process was controlled in aknown manner to produce a sized fiber product having a moisture contentin the range of 13-17 wt. percent with an average of about 15 wt.percent and an LOI in the range of 0.13-0.19 wt. percent and an averageLOI of about 0.16 wt. percent on the basis of dry fiber weight. Thefiber product was packaged in sealed plastic bags and shipped to agypsum board manufacturer. When this fiber product was added to plainplant water, the fiber dispersed quickly and uniformly and substantiallybetter than the fiber product being used in production, and produced agypsum board having a superior uniformity of fiber content throughoutthe board product.

[0024] When the word “about” is used herein it is meant that the amountor condition it modifies may vary so long as the advantages of theinvention are realized. The skilled artisan understands this and expectsthat the disclosed results of the invention might extend, at leastsomewhat, beyond one or more of the limits disclosed. Later, having thebenefit of the inventors disclosure and understanding the inventiveconcept and embodiments disclosed including the best mode known to theinventor, the inventor and others can, without inventive effort, explorebeyond the limits disclosed to determine if the invention is realizedbeyond those limits and, when embodiments are found to be withoutunexpected characteristics, those embodiments are within the meaning ofthe term about as used herein. It is not difficult for the skilledartisan or others to determine whether such an embodiment is either asmight be expected or, because of either a break in the continuity ofresults or one or more features that are significantly better thanreported by the inventor, is surprising and thus an unobvious teachingleading to a further advance in the art.

[0025] Having disclosed the preferred embodiments of the invention andits uses in detail above, other modifications and uses will be apparentto the skilled artisan which modifications and uses are encompassed inthe following claims.

1. A staple fiber product, comprising fibers having a chemical sizinghaving a level of surfactant on the surfaces in an amount to produce anLOI of the fiber in the range of about 0.8 to about 0.24 wt. percent, ona dry fiber basis, said sizing containing one or more surfactants in anamount such that the surfactant level is responsible for least about 30weight percent of the LOI.
 2. The fiber product of claim 1 wherein saidfibers are glass fibers.
 3. The fiber product of claim 2 wherein saidsizing further comprises a film forming polymer in an amount of up to 50wt. percent of the LOI.
 4. The fiber product of claim 3 wherein saidsizing is present on said fibers in an amount in the range of about0.13-0.19 wt. percent.
 5. The fiber product of claim 4 wherein the fiberis wet and has a moisture content in the range of about 5-25 wt.percent, based on the dry fiber weight.
 6. The fiber product of claim 5wherein a biocide is present in an effective amount to prevent bacterialor microbial action.
 7. The fiber product of claim 2 wherein thesurfactant is a cationic surfactant.
 8. The fiber product of claim 7wherein the film former is polyvinyl alcohol and the glass is E glass.9. The fiber product of claim 7 wherein the cationic surfactant is apoly (Oxy-1,2-ethanediyl), alpha(2-(bis(2-Aminoethyl) Methyl-ammonio)Ethyl)-omega-Hydroxy-,N,N′-Di(C 14-18 and C 16-18 unsaturated) AcylDerivs., Me Sulfate (Salts) and is responsible for about 40-50 percentof the LOI, the film former is polyvinyl alcohol and is responsible forabout 39-46 percent of the LOI, the glass is E glass and the moisturecontent of the glass fiber product is between about 5-25 wt. percent.10. The fiber product of claim 7 wherein the amount of sizing on thefiber is in the range of about 0.13-0.19 wt. percent, the cationicsurfactant is a poly (Oxy-1,2-ethanediyl), alpha(2-(bis(2-Aminoethyl)Methyl-ammonio) Ethyl)-omega-Hydroxy-,N,N′-Di(C 14-18 and C 16-18unsaturated) Acyl Derivs., Me Sulfate (Salts) and is responsible forabout 40-50 percent of the LOI, the film former is polyvinyl alcohol andis responsible for about 30-46 percent of the LOI, the glass is E glassand the moisture content of the glass fiber product is in the range ofabout 15+/−5 wt. percent.
 11. A glass fiber sizing compositionconsisting essentially of water and a surfactant level in an amount ofabout 0.1-1.2 wt. percent of the sizing composition.
 12. The sizingcomposition of claim 11 wherein the surfactant comprises Methylbis(Alkylamidoethyl) 2-Hydroxyethyl Ammonium Methyl Sulfate, Ethoxylatedsurfactant.
 13. The sizing composition of claim 12 wherein the sizingcomposition also comprises a film former polymer.
 14. The sizingcomposition of claim 13 wherein the film forming polymer is a polyvinylalcohol and is present in an amount in the range of up to 1.5 wt.percent of the sizing.
 15. The sizing composition of claim 14 whereinthe surfactant is present in an amount in the range of 0.3-0.9 wt.percent and the polyvinyl alcohol is present in an amount in the rangeof 0.3-0.7 wt. percent.
 16. The sizing composition of claim 15 whereinthe composition also comprises an effective amount of a biocide toprevent bacterial or microbial action.
 17. The sizing of claim 15wherein the surfactant is a cationic surfactant.
 18. The sizing of claim17 wherein the surfactant comprises 0.5-0.7 wt. Percent in the sizing,the polyvinyl alcohol comprises 0.4-0.6 wt. percent and a biocide ispresent in an amount to effectively prevent bacterial or microbialaction.
 19. A method of making a sized fiber that disperses quickly anduniformly in plant water comprising forming glass fibers, applying anaqueous chemical sizing composition to the glass fibers and chopping theglass fibers into discrete lengths; selecting an aqueous sizingcomposition containing surfactant level of 0.1-1.2 wt. percent, based onthe weight of the sizing, and up to 1.5 wt. percent of a polymer filmformer and applying this sizing composition in an amount to produce anLOI on the fiber in the range of about 0.08-0.24 wt. percent, based onthe weight of the dry fiber, the cationic surfactant being responsiblefor at least 30 percent of the LOI.
 20. The method of claim 19 whereinthe surfactant includes a cationic surfactant product.
 21. A method ofmaking a fiber reinforced product in a process comprising selecting aglass fiber product containing a chemical sizing thereon, said sizinghaving a surfactant level on the fiber in an amount in the range of0.8-0.24 wt. percent, based on the weight of dried fiber, wherein thesizing contains 30-60 wt. percent, on a dry basis, of a surfactant and20-50 wt. percent on the same basis of a polymer film former; dispersingfiber in plant water; forming a fiber reinforced product.
 22. The methodof claim 21, wherein the fiber reinforced product is fiberglassreinforced gypsum board.